How it works
Nico had no coins with him, so he tapped a card for a hat that cost 4 pretend coins. The hat was not free.
Behind the card is a bank. The bank paid Zed 4 coins right away, and now Nico owes the bank.
A credit card lets us borrow from a bank while we shop. The bank sets a top number of coins, called the limit.
At the month's end a bill lists each thing and its coins. If a bill waits too long, the bank may ask for extra coins.